Test a monitor, laptop, phone, or tablet screen online. Use 13 full-screen patterns to find dead or stuck pixels, bleed, clouding, banding, tint, and scaling issues, then measure refresh rate.
Patterns are drawn in this browser tab
What this browser reports about the screen you are looking at.
Open a pattern to fill the display. Arrow keys move between patterns, Escape exits.
Two things that prevent a false result.
Clean the screen with a dry microfibre cloth first. Dust and smears look exactly like dead pixels on a white field.
Complete tool guide
Use this online monitor and screen test to expose dead or stuck pixels, failed color sub-pixels, backlight bleed, clouding, grayscale clipping, color banding, tint, and non-native scaling with controlled full-screen patterns.
Your input is processed in the current browser tab and is not sent to the application server.
Clean the screen first so dust is not mistaken for a dead pixel.
Open a pattern to fill the display.
Use the arrow keys or click to move between patterns.
Press Escape to leave full screen when you are done.
Screen size is reported in CSS pixels; native resolution estimates device pixels using the pixel ratio. Color depth and gamut describe the browser's display pipeline, while refresh rate is estimated from delivered animation frames.
Runs a fresh foreground frame-timing sample. Keep this tab visible, disable power saving, and stop heavy animation or video elsewhere; an uneven-timing warning means the result should be repeated.
Black reveals bright stuck pixels, edge glow, and clouding; white reveals dark dead pixels and dirty or shaded areas. Clean the panel first and inspect black in a dim room.
Primary and combined color fields isolate weak or failed sub-pixels. A dot that stays dark or the wrong color on one field identifies which red, green, or blue component is not responding normally.
Every block from black to white should remain distinguishable. Merged dark steps suggest crushed shadow detail; merged bright steps suggest clipped highlights or an unsuitable display range setting.
These should transition continuously. Visible bands can come from low color depth, compression, HDR or driver settings; tint or a strong change with viewing angle can indicate panel uniformity limitations.
The one-pixel grid should remain crisp and stable. Blur, moiré, or shimmer often means the display is scaled or is not using its native resolution.
A neutral gray field makes uneven brightness, colored patches, dirty-screen effect, and edge tint easier to see than normal content does.
Open any pattern, then click the field or use Next and Previous to cycle through all 13. Arrow keys also move between patterns; Exit or Escape returns to the page.
A dead pixel stays black on every pattern. A stuck pixel stays lit in one color and shows up as a bright dot on the black pattern. Stuck pixels sometimes recover on their own; dead pixels do not.
On the black pattern in a dark room, glow at the edges is backlight bleed and patchy brightness in the middle is clouding. Some of both is normal on LCD panels; large bright patches are not.
The rate is measured from how often the browser paints a frame. Background tabs and power-saving modes throttle painting, so measure with this tab in the foreground and the device on mains power.
Manufacturers publish their own thresholds, and many allow a small number before a panel qualifies for replacement. Check the warranty terms for your specific model.
Browsers cap painting to the display refresh rate but throttle it when a tab is inactive, when the device is on battery, or when the system is busy. Keep the tab focused and try again.
Rapidly cycling colors sometimes revives a stuck pixel, and stepping quickly through these patterns has the same effect. There is no guarantee, and a truly dead pixel cannot be recovered in software.
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